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9170Re: [tracker2] How to deal with GPS drift with OT2?

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  • Keith VE7GDH
    Nov 2, 2009
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      Bernard KI6TSF wrote...

      > I got a brand new GlobalSat BR-355 SiRF GPS which I use on
      > the secondary port of the OT2. Unfortunately, I discovered
      > that the position is drifting severely when the car is parked
      > for several hours at the same place (covered or uncovered),
      > sometimes up to 300ft. This may be due to reflections.

      Why would it "drift" more when parked compared to mobile? Hopefully you
      are using SmartBeaconing and have it backed off to something like 10-30
      minutes for the slow rate if you are going to leave it on all the time.
      I use 10 minutes for the slow rate in SmartBeaconing, but then again,
      it's turned off when parked.

      I too would be curious too about the accuracy of the GPS receiver. Take
      the OT2 right out of the picture. Connect the GPS to a computer and
      watch it in something like VisualGPS to see what is going on. You could
      of course just view the NMEA strings in a terminal program, but
      VisualGPS is a freebie download and I know there are other programs that
      do the same thing. Do you see your position wandering everywhere, or
      just when you are parked in one particular spot? There could be
      something interfering with the GPS receiver.

      > I tried with WAAS enabled and disabled, and with Static Navigation
      > enabled and disabled and get the same problem. Static Navigation is
      > supposed to fix this by correcting the coordinates if the calculated
      > position moves slower than 1.6 m/s. It does not work: calculated
      > moves are grater than that.

      What do you mean by "Static Navigation"? Do you mean entering a fixed
      position into the OT2 rather than getting the position from the GPS? If
      you enter a fixed position, the position shouldn't change at all. Or is
      this some setting in that particular GPS receiver?

      73 es cul - Keith VE7GDH
      "I may be lost, but I know exactly where I am!"
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